Chuck Bednar for redOrbit.com – @BednarChuck
One of the reasons lettuce is so healthy is because it is rich in antioxidants, which protect our bodies from molecules that cause cell damage and create a variety of diseases. But a new study indicates that not all types of lettuce are created equal.
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According to researchers from the UPV/EHU-University of the Basque Country, the color of the leafy vegetable determines how quickly their antioxidant compounds work in limited the impact of free radicals, which can cause aging, lead to serious illness, or otherwise harm our health.
In a recent edition of the Journal of Agricultural and Food Chemistry, lead investigator Usue Pérez-López of the Department of Plant Biology and Ecology of the UPV/EHU’s Faculty of Science and Technology and her colleagues report that the antioxidants found in lettuce with green leaves react more slowly that versions of the vegetable with red leaves.
Starting in 2011, Pérez-López and her team began analyzing the compounds of three different varieties of lettuce: green-leafed “Batavia,” semi-red-leafed “Marvel of Four Seasons,” and red-leafed “Oak Leaf” using Electron Paramagnetic Resonance (EPR) techniques.
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By monitoring their decay kinetics, they found that the green-leaf lettuce contained water-soluble, antioxidant compounds which act at slow and intermediate speeds, while the red-leaf lettuce had compounds that act at intermediate and rapid speeds, and the semi-red-leaf one had three kinds of compounds that act at slow, rapid, and intermediate speeds.
“The results showed that as long as lettuce had higher red pigmentation, the hydrophilic antioxidant capacity increased together with the contents in free and conjugated phenolic acids, free and conjugated flavonoids, and anthocyanins,” Pérez-López and her co-authors wrote.
At this time, they cannot tell for sure which antioxidants are responsible for which of these kinetic behaviors, but they suggest that the flavonoid quercetin accounted for the majority of the intermediate-rate antioxidants, while anthocyanins accounted for most of the fast-rate ones.
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All lettuce is good for you
“The fact that there are compounds that act at different speeds does not mean that some are better or worse than others,” Pérez-López said. “If we eat foods that can generate free-radical activity, there will be some compounds that act to eliminate them more quickly.”
“But at the same time, it is also important that our bodies should acquire foods with antioxidants that have slower kinetics so that the latter will continue to act over a longer period of time,” she added. “That is why people say that it is very interesting to mix different types of lettuce because they have different, complementary characteristics.”
The next step is to find a way to improve the nutritional and pharmaceutical properties of all three varieties of lettuce, the researchers said. They are currently attempting to find a way to up the effects of specific compounds in each variety by subjecting the plants to short stresses. Since these compounds have a defense-related function in plants, subjecting them to conditions other than what they are used to could boost their antioxidant qualities.
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“What matters in this process is not to lose productivity, and that is why we apply short-intensity stresses,” Pérez-López explained. “With excessive stress, we could reach a point in which plant growth is reduced, and we are not interested in achieving greater quality at the cost of a reduction in size. The aim is to maintain production and achieve greater quality in this production.”
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